- Email: [email protected]
Antimicrobial blue light inactivation of international clones of multidrug-resistant Escherichia coli ST10, ST131 and ST648
Photodiagnosis and Photodynamic Therapy 27 (2019) 51–53
Contents lists available at ScienceDirect
Photodiagnosis and Photodynamic Therapy journal homepage: www.elsevier.com/locate/pdpdt
Short communication
Antimicrobial blue light inactivation of international clones of multidrugresistant Escherichia coli ST10, ST131 and ST648
T
⁎
Carolina dos Anjosa, Caetano P. Sabinob,c, , Vanessa Buerisd, Miriam R. Fernandesb, ⁎ Fabio C. Pogliania, Nilton Lincopanb,d, Fábio P. Selleraa, a
Department of Internal Medicine, School of Veterinary Medicine and Animal Science, University of Sao Paulo, Sao Paulo, SP, Brazil Department of Clinical and Toxicological Analysis, School of Pharmaceutical Sciences, University of Sao Paulo, Sao Paulo, SP, Brazil c BioLambda, Scientific and Commercial LTD, Sao Paulo, SP, Brazil d Department of Microbiology, Institute for Biomedical Sciences, University of Sao Paulo, Sao Paulo, SP, Brazil b
A R T I C LE I N FO
A B S T R A C T
Keywords: Carbapenems Colistin ESBL KPC-2 MCR-1 Photoinactivation Antimicrobial Photodynamic Therapy
Background: International clones of multidrug-resistant Escherichia coli have been a leading cause of human and animal infections worldwide. Microbial inactivation by blue light has been proposed as an effective treatment for superficial infections and surface contamination. Aim: To evaluate the inactivation efficacy of blue light irradiation against high-risk multidrug-resistant strains of E. coli. Methods: Blue LED light (λ = 410 nm) was used to inactivate in vitro suspensions of colistin- broad-spectrum cephalosporin-, or carbapenem-resistant E. coli strains belonging to sequence types (STs) ST10, ST131 and ST648, carrying mcr-1, blaCTX-M or blaKPC-2 genes. Results: Our results showed that all E. coli strains were susceptible to blue light irradiation, independently of antibiotic resistance and virulence profiles. In addition, blue light irradiation induced a strain-specific and dosedependent bacterial effect. Conclusion: Our results support use of blue light as a promising antimicrobial option against MDR pathogens, including high-risk clones of E. coli displaying resistance to polymyxins or broad-spectrum β-lactam antibiotics.
1. Background
2. Aims
The rapid dissemination of multidrug-resistant (MDR) pathogens has triggered interest in alternatives to antibiotics therapy for infection control [1]. Escherichia coli strains belonging to sequence types (STs) ST10, ST131 and ST648 have been emerging as a versatile prototype of MDR pathogens for human and animal hosts [2]. Worryingly, the convergence of antimicrobial resistance with enhanced virulence also begun to be reported among these E. coli strains [2,3]. Microbial inactivation mediated by blue light represents a promising therapeutic procedure to treat superficial infections. Blue light has intrinsic antimicrobial properties as it can be absorbed by natural pigments, such as porphyrins and flavins, leading to photochemical production of reactive oxygen species (ROS). Cellular exposure to ROS allows damage to vital structures and, in sufficient amounts, cause microbial inactivation [4,5].
The aim of the study was to investigate the kinetics of blue light inactivation of high-risk MDR E. coli strains.
⁎
3. Methods We used three wild-type E. coli strains previously characterized: 1) CTX-M-producing E. coli belonging to ST131; 2) KPC-2-producing E. coli belonging to ST648 [6]; and 3) MCR-1-producing E. coli belonging to ST10 [7]. All strains displayed MDR profile [8]. Additionally, a drugsensitive strain (ATCC® 25922™) was used as control and an enteropathogenic strain O127:H7 (E2348/69) [9] was used as a typical virulent strain. Fresh individual colonies were collected from MacConkey agar (Difco, USA) and inoculated into 3 mL of Mueller-Hinton broth (Difco, USA) before being incubated at 37 °C for 24 h under shaking regimen (100 RPM). Then, bacterial cultures were washed twice and suspended
Corresponding authors at: Av. Prof. Dr. Orlando Marques de Paiva, 87 - Cidade Universitária, 05508 - 270, São Paulo, SP, Brazil. E-mail addresses: [email protected] (C.P. Sabino), [email protected] (F.P. Sellera).
https://doi.org/10.1016/j.pdpdt.2019.05.014 Received 9 April 2019; Received in revised form 7 May 2019; Accepted 13 May 2019 Available online 14 May 2019 1572-1000/ © 2019 Elsevier B.V. All rights reserved.
Photodiagnosis and Photodynamic Therapy 27 (2019) 51–53
C. dos Anjos, et al.
inactivation kinetics. In fact, statistical analysis revealed significant variation in survival fraction levels within different strains at the same light doses. The CTX-M-producing E. coli ST131 (ICBECMO) presented more than 5 log inactivation after exposure to 90 min (206.25 J/cm2). This strain was the most susceptible when compared to all other tested strains, including the E. coli ATCC 25922 strain. The virulent E. coli 0127:H7 strain (E2348/69) presented more than 3.4 log of inactivation at 150 min (343.75 J/cm2). E. coli ATCC 25922 and MCR-1-producing E. coli ST10 (ICBEC7P) strains exhibited more than 3.7 log of inactivation at 180 min (412.50 J/cm2). The KPC-2-producing E. coli ST648 (ECSIC19) was the most tolerant strain, however, 2.8 log of inactivation was achieved after 180 min of irradiation (412.50 J/cm2). At the same dose, we observed complete inactivation of CTX-M-producing ST131 (ICBECMO) and 0127:H7 (E2348/69) E. coli strains.
Table 1 Exposure time and radiant exposure (J/cm2) of blue light used for inactivation kinetics curves of MDR Escherichia coli strains belonging to international clones ST10, ST131 and ST648. Irradiation parameters Minutes J/cm2
30 68.75
60 137.50
90 206.25
120 275.01
150 343.75
180 412.50
in PBS to prepare the experimental inoculum. The inocula were standardized to approximately 109 colony forming unit (CFU)/mL by assessing the turbidity of the suspension with a spectrophotometer (λabs = 625 nm; optical path = 1 cm; optical density = 0.667). We used a commercial cell-culture plate irradiation system with peak wavelength emission at 410 +/- 10 nm and irradiance level of 38.2 mW/cm2 (LEDbox, BioLambda, São Paulo, Brazil). One-mL inoculum of each experimental group was individually placed in wells of 12-well plates. All samples were irradiated with more than 95% of beam homogeneity. Each light exposure group of each strain (Table 1) was compared to other strain counterparts at the same light dose. After treatments, samples were serially diluted (1:10) in sterile PBS, seeded onto Muller Hinton agar plates and incubated at 37 °C for 24 h. CFU quantification was performed according to the methodology described by Jett et al. [10]. All experiments were performed in triplicates and reproduced in three independent experiments. Survival fraction values were determined as the averages of log10 reduction of CFU normalized in relation to each respective control group. Survival fraction data was tested to confirm normality (ShapiroWilk test) and compared in between strains using multiple comparisons of two-way analysis of variance (ANOVA) followed by Tukey test. Statistical tests were performed using Prism software (GraphPad, USA). Significance level was considered at p < 0.05.
5. Discussion Regardless of the vast literature about the use of blue light to inactivate pathogenic bacteria [11], no studies have yet reported its use against international clones of high-risk E. coli. Likewise, there is no comparison of blue light inactivation of MDR E. coli carrying the clinically important resistance genes blaCTX-M, blaKPC-2 and mcr-1, which emphasizes the novelty of this investigation. Infections caused by such high-risk strains are often resistant to most commercially available antibiotics, including to the last resort drugs (e.g. carbapenems and polymyxins) [2,3,12,13]. Interestingly, even though the CTX-M-producing E. coli ST131 is a serious concern worldwide, it was the most sensitive strain to blue light exposure. These findings suggest that susceptibility to blue light irradiation is probably associated with intrinsic metabolic characteristics that are not related to drug-resistance profile. In fact, each tested E. coli strain may have intrinsic biochemical characteristics that determine their sensitivity to blue light unique. This uniqueness could be related to concentration of endogenous photosensitive pigments (eg., porphyrin and flavin derivatives), which could range among bacterial strains from the same species. After 180 min of irradiation, we observed that all tested E. coli strains presented more than 3log10 inactivation by blue light. In this regard, hospitalized patients infected by MDR strains frequently stay isolated in intensive care units and can be continuously irradiated throughout the entire day. Additionally, there may not be any other therapeutic options available. Other studies corroborate to our results demonstrating that blue light irradiation is able to inactivate drug-resistant pathogens. Studies performed with bacterial suspensions, biofilms and infections confirmed the successful use of blue light in the treatment of MDR Staphylococcus aureus, Acinetobacter baumannii and Pseudomonas aeruginosa [14–16]. In summary, our results showed that blue light irradiation induced a dose-dependent bactericidal effect against all tested E. coli strains regardless of antibiotic resistance and virulence profiles. Therefore, blue light represents an effective approach against high-risk MDR E. coli isolates opening a new avenue for innovative therapeutic platforms.
4. Results In this study, all tested E. coli strains were susceptible to blue light inactivation. All irradiated groups presented significant differences in relation to their respective non-irradiated control groups. In Fig. 1, it is possible to observe that blue light irradiation induced strain-specific
Conflict of interest C. P. Sabino is an associate at BioLambda company but declares to only have scientific interest on this study. There are no further conflicts of interest to be declared.
Fig. 1. Survival fraction of MDR Escherichia coli strains inactivation induced by blue light irradiation. The results are presented as normalized survival fractions of log10 reduction in function of irradiation time. The error bars are standard deviation of each mean. Statistical differences are indicated by lower-case letters: a) represent differences in relation to the control strain, b) to the 0127:H7 strain, c) to the CTX-M-producing E. coli ST131 strain, d) to the MCR-1-positive E. coli ST10 strain and e) to the KPC-2-producing E. coli ST648 strain. Data is omitted in points where inactivation rate is greater than 7log10 such as for CTXM ST131 at irradiation times greater than 120 min and for KPC-2 ST648 at 180 min.
Acknowledgments We gratefully thank the Brazilian funding agency FAPESP (grants 2016/25095-2, 2016/08593-9 and 2015/13527-2), CAPES (Finance Code 001), CNPq (grant 141901/2016-0 and 312249/2017-9, 462042/ 2014-6 and 433128/2018-6), and technical support offered by the start52
Photodiagnosis and Photodynamic Therapy 27 (2019) 51–53
C. dos Anjos, et al.
up company BioLambda. N. L. is research fellow of CNPq (312249/ 2017-9). References
[9]
[1] A.J. Mathers, G. Peirano, J.D.D. Pitout, The role of epidemic resistance plasmids and international high-risk clones in the spread of multidrug-resistant Enterobacteriaceae, Clin. Microbiol. Rev. 28 (2015) 565–591, https://doi.org/10. 1128/CMR.00116-14. [2] F.P. Sellera, N. Lincopan, Zooanthroponotic transmission of high-risk multidrugresistant pathogens: a neglected public health issue, J. Infect. Public Health 12 (2019) 294–295, https://doi.org/10.1016/j.jiph.2018.12.013. [3] I. García-Meniño, V. García, A. Mora, D. Díaz-Jiménez, S.C. Flament-Simon, M.P. Alonso, et al., Swine enteric colibacillosis in Spain: pathogenic potential of mcr-1 ST10 and ST131 E. coli isolates, Front. Microbiol. 9 (2018) 1–15, https://doi. org/10.3389/fmicb.2018.02659. [4] T. Dai, A. Gupta, C.K. Murray, M.S. Vrahas, G.P. Tegos, M.R. Hamblin, Blue Light for infectious diseases: Propionibacterium acnes, Helicobacter pylori, and beyond? Drug Resist. Updat. 15 (2013) 223–236, https://doi.org/10.1016/j.drup.2012.07. 001.Blue. [5] C. Anjos, F.P. Sellera, R.G. Gargano, N. Lincopan, F.C. Pogliani, M.G. Ribeiro, et al., Algicidal effect of blue light on pathogenic Prototheca species, Photodiagn. Photodyn. Ther. 26 (2019) 210–213, https://doi.org/10.1016/j.pdpdt.2019.04. 009. [6] F.P. Sellera, M.R. Fernandes, R. Ruiz, A.C.M. Falleiros, F.P. Rodrigues, L. Cerdeira, et al., Identification of KPC-2-producing Escherichia coli in a companion animal: a new challenge for veterinary clinicians, J. Antimicrob. Chemother. 73 (2018) 2259–2261, https://doi.org/10.1093/jac/dky173. [7] F.P. Sellera, M.R. Fernandes, L. Sartori, M.P.N. Carvalho, F. Esposito, C.L. Nascimento, et al., Escherichia coli carrying IncX4 plasmid-mediated mcr-1 and blaCTX-M genes in infected migratory Magellanic penguins (Spheniscus magellanicus), J. Antimicrob. Chemother. 72 (2017) 1255–1256, https://doi.org/10.1093/jac/ dkw543. [8] A.P. Magiorakos, A. Srinivasan, R.B. Carey, Y. Carmeli, M.E. Falagas, C.G. Giske,
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[12]
[13]
[14]
[15]
[16]
53
et al., Multidrug-resistant, extensively drug-resistant and pandrug-resistant bacteria: an international expert proposal for interim standard definitions for acquired resistance, Clin. Microbiol. Infect. 18 (2012) 268–281, https://doi.org/10.1111/j. 1469-0691.2011.03570.x. M.M. Levine, D.R. Nalin, R.B. Hornick, E.J. Bergquist, D.H. Waterman, C.R. Young, et al., Escherichia coli strains that cause diarrhoea but do not produce heat-labile or heat-stable enterotoxins and are non-invasive, Lancet 311 (1978) 1119–1122, https://doi.org/10.1016/S0140-6736(78)90299-4. B.D. Jett, K.L. Hatter, M.M. Huycke, M.S. Gilmore, Simplified agar plate method for quantifying viable bacteria, Biotechniques 23 (1997) 648–650. Y. Wang, Y. Wang, Y. Wang, C.K. Murray, M.R. Hamblin, D.C. Hooper, et al., Antimicrobial blue light inactivation of pathogenic microbes: state of the art, Drug Resist. Updat. 33–35 (2017) 1–22, https://doi.org/10.1016/j.drup.2017.10.002. C. Ewers, A. Bethe, I. Stamm, M. Grobbel, B. Guerra, M. Stubbe, P.A. Kopp, et al., CTX-M-15-D-ST648 Escherichia coli from companion animals and horses: another pandemic clone combining multiresistance and extraintestinal virulence? J. Antimicrob. Chemother. 69 (2014) 1224–1230, https://doi.org/10.1093/jac/ dkt516. B.A. Rogers, H.E. Sidjabat, D.L. Paterson, Escherichia coli O25b-ST131: a pandemic, multiresistant, community-associated strain, J. Antimicrob. Chemother. 66 (2011) 1–14, https://doi.org/10.1093/jac/dkq415. G. Fila, A. Kawiak, M.S. Grinholc, Blue light treatment of Pseudomonas aeruginosa: strong bactericidal activity, synergism with antibiotics and inactivation of virulence factors, Virulence 8 (2017) 938–958, https://doi.org/10.1080/21505594.2016. 1250995. P. Yang, N. Wang, C. Wang, Y. Yao, X. Fu, W. Yu, et al., 460 nm visible light irradiation eradicates MRSA via inducing prophage activation, J. Photochem. Photobiol. B: Biol. 166 (2017) 311–322, https://doi.org/10.1016/j.jphotobiol. 2016.12.001. Y. Zhang, Y. Zhu, A. Gupta, Y. Huang, C.K. Murray, M.S. Vrahas, et al., Antimicrobial blue light therapy for multidrug-resistant Acinetobacter baumannii infection in a mouse burn model: implications for prophylaxis and treatment of combat-related wound infections, J. Infect. Dis. 209 (2014) 1963–1971, https://doi. org/10.1093/infdis/jit842.
Contents lists available at ScienceDirect
Photodiagnosis and Photodynamic Therapy journal homepage: www.elsevier.com/locate/pdpdt
Short communication
Antimicrobial blue light inactivation of international clones of multidrugresistant Escherichia coli ST10, ST131 and ST648
T
⁎
Carolina dos Anjosa, Caetano P. Sabinob,c, , Vanessa Buerisd, Miriam R. Fernandesb, ⁎ Fabio C. Pogliania, Nilton Lincopanb,d, Fábio P. Selleraa, a
Department of Internal Medicine, School of Veterinary Medicine and Animal Science, University of Sao Paulo, Sao Paulo, SP, Brazil Department of Clinical and Toxicological Analysis, School of Pharmaceutical Sciences, University of Sao Paulo, Sao Paulo, SP, Brazil c BioLambda, Scientific and Commercial LTD, Sao Paulo, SP, Brazil d Department of Microbiology, Institute for Biomedical Sciences, University of Sao Paulo, Sao Paulo, SP, Brazil b
A R T I C LE I N FO
A B S T R A C T
Keywords: Carbapenems Colistin ESBL KPC-2 MCR-1 Photoinactivation Antimicrobial Photodynamic Therapy
Background: International clones of multidrug-resistant Escherichia coli have been a leading cause of human and animal infections worldwide. Microbial inactivation by blue light has been proposed as an effective treatment for superficial infections and surface contamination. Aim: To evaluate the inactivation efficacy of blue light irradiation against high-risk multidrug-resistant strains of E. coli. Methods: Blue LED light (λ = 410 nm) was used to inactivate in vitro suspensions of colistin- broad-spectrum cephalosporin-, or carbapenem-resistant E. coli strains belonging to sequence types (STs) ST10, ST131 and ST648, carrying mcr-1, blaCTX-M or blaKPC-2 genes. Results: Our results showed that all E. coli strains were susceptible to blue light irradiation, independently of antibiotic resistance and virulence profiles. In addition, blue light irradiation induced a strain-specific and dosedependent bacterial effect. Conclusion: Our results support use of blue light as a promising antimicrobial option against MDR pathogens, including high-risk clones of E. coli displaying resistance to polymyxins or broad-spectrum β-lactam antibiotics.
1. Background
2. Aims
The rapid dissemination of multidrug-resistant (MDR) pathogens has triggered interest in alternatives to antibiotics therapy for infection control [1]. Escherichia coli strains belonging to sequence types (STs) ST10, ST131 and ST648 have been emerging as a versatile prototype of MDR pathogens for human and animal hosts [2]. Worryingly, the convergence of antimicrobial resistance with enhanced virulence also begun to be reported among these E. coli strains [2,3]. Microbial inactivation mediated by blue light represents a promising therapeutic procedure to treat superficial infections. Blue light has intrinsic antimicrobial properties as it can be absorbed by natural pigments, such as porphyrins and flavins, leading to photochemical production of reactive oxygen species (ROS). Cellular exposure to ROS allows damage to vital structures and, in sufficient amounts, cause microbial inactivation [4,5].
The aim of the study was to investigate the kinetics of blue light inactivation of high-risk MDR E. coli strains.
⁎
3. Methods We used three wild-type E. coli strains previously characterized: 1) CTX-M-producing E. coli belonging to ST131; 2) KPC-2-producing E. coli belonging to ST648 [6]; and 3) MCR-1-producing E. coli belonging to ST10 [7]. All strains displayed MDR profile [8]. Additionally, a drugsensitive strain (ATCC® 25922™) was used as control and an enteropathogenic strain O127:H7 (E2348/69) [9] was used as a typical virulent strain. Fresh individual colonies were collected from MacConkey agar (Difco, USA) and inoculated into 3 mL of Mueller-Hinton broth (Difco, USA) before being incubated at 37 °C for 24 h under shaking regimen (100 RPM). Then, bacterial cultures were washed twice and suspended
Corresponding authors at: Av. Prof. Dr. Orlando Marques de Paiva, 87 - Cidade Universitária, 05508 - 270, São Paulo, SP, Brazil. E-mail addresses: [email protected] (C.P. Sabino), [email protected] (F.P. Sellera).
https://doi.org/10.1016/j.pdpdt.2019.05.014 Received 9 April 2019; Received in revised form 7 May 2019; Accepted 13 May 2019 Available online 14 May 2019 1572-1000/ © 2019 Elsevier B.V. All rights reserved.
Photodiagnosis and Photodynamic Therapy 27 (2019) 51–53
C. dos Anjos, et al.
inactivation kinetics. In fact, statistical analysis revealed significant variation in survival fraction levels within different strains at the same light doses. The CTX-M-producing E. coli ST131 (ICBECMO) presented more than 5 log inactivation after exposure to 90 min (206.25 J/cm2). This strain was the most susceptible when compared to all other tested strains, including the E. coli ATCC 25922 strain. The virulent E. coli 0127:H7 strain (E2348/69) presented more than 3.4 log of inactivation at 150 min (343.75 J/cm2). E. coli ATCC 25922 and MCR-1-producing E. coli ST10 (ICBEC7P) strains exhibited more than 3.7 log of inactivation at 180 min (412.50 J/cm2). The KPC-2-producing E. coli ST648 (ECSIC19) was the most tolerant strain, however, 2.8 log of inactivation was achieved after 180 min of irradiation (412.50 J/cm2). At the same dose, we observed complete inactivation of CTX-M-producing ST131 (ICBECMO) and 0127:H7 (E2348/69) E. coli strains.
Table 1 Exposure time and radiant exposure (J/cm2) of blue light used for inactivation kinetics curves of MDR Escherichia coli strains belonging to international clones ST10, ST131 and ST648. Irradiation parameters Minutes J/cm2
30 68.75
60 137.50
90 206.25
120 275.01
150 343.75
180 412.50
in PBS to prepare the experimental inoculum. The inocula were standardized to approximately 109 colony forming unit (CFU)/mL by assessing the turbidity of the suspension with a spectrophotometer (λabs = 625 nm; optical path = 1 cm; optical density = 0.667). We used a commercial cell-culture plate irradiation system with peak wavelength emission at 410 +/- 10 nm and irradiance level of 38.2 mW/cm2 (LEDbox, BioLambda, São Paulo, Brazil). One-mL inoculum of each experimental group was individually placed in wells of 12-well plates. All samples were irradiated with more than 95% of beam homogeneity. Each light exposure group of each strain (Table 1) was compared to other strain counterparts at the same light dose. After treatments, samples were serially diluted (1:10) in sterile PBS, seeded onto Muller Hinton agar plates and incubated at 37 °C for 24 h. CFU quantification was performed according to the methodology described by Jett et al. [10]. All experiments were performed in triplicates and reproduced in three independent experiments. Survival fraction values were determined as the averages of log10 reduction of CFU normalized in relation to each respective control group. Survival fraction data was tested to confirm normality (ShapiroWilk test) and compared in between strains using multiple comparisons of two-way analysis of variance (ANOVA) followed by Tukey test. Statistical tests were performed using Prism software (GraphPad, USA). Significance level was considered at p < 0.05.
5. Discussion Regardless of the vast literature about the use of blue light to inactivate pathogenic bacteria [11], no studies have yet reported its use against international clones of high-risk E. coli. Likewise, there is no comparison of blue light inactivation of MDR E. coli carrying the clinically important resistance genes blaCTX-M, blaKPC-2 and mcr-1, which emphasizes the novelty of this investigation. Infections caused by such high-risk strains are often resistant to most commercially available antibiotics, including to the last resort drugs (e.g. carbapenems and polymyxins) [2,3,12,13]. Interestingly, even though the CTX-M-producing E. coli ST131 is a serious concern worldwide, it was the most sensitive strain to blue light exposure. These findings suggest that susceptibility to blue light irradiation is probably associated with intrinsic metabolic characteristics that are not related to drug-resistance profile. In fact, each tested E. coli strain may have intrinsic biochemical characteristics that determine their sensitivity to blue light unique. This uniqueness could be related to concentration of endogenous photosensitive pigments (eg., porphyrin and flavin derivatives), which could range among bacterial strains from the same species. After 180 min of irradiation, we observed that all tested E. coli strains presented more than 3log10 inactivation by blue light. In this regard, hospitalized patients infected by MDR strains frequently stay isolated in intensive care units and can be continuously irradiated throughout the entire day. Additionally, there may not be any other therapeutic options available. Other studies corroborate to our results demonstrating that blue light irradiation is able to inactivate drug-resistant pathogens. Studies performed with bacterial suspensions, biofilms and infections confirmed the successful use of blue light in the treatment of MDR Staphylococcus aureus, Acinetobacter baumannii and Pseudomonas aeruginosa [14–16]. In summary, our results showed that blue light irradiation induced a dose-dependent bactericidal effect against all tested E. coli strains regardless of antibiotic resistance and virulence profiles. Therefore, blue light represents an effective approach against high-risk MDR E. coli isolates opening a new avenue for innovative therapeutic platforms.
4. Results In this study, all tested E. coli strains were susceptible to blue light inactivation. All irradiated groups presented significant differences in relation to their respective non-irradiated control groups. In Fig. 1, it is possible to observe that blue light irradiation induced strain-specific
Conflict of interest C. P. Sabino is an associate at BioLambda company but declares to only have scientific interest on this study. There are no further conflicts of interest to be declared.
Fig. 1. Survival fraction of MDR Escherichia coli strains inactivation induced by blue light irradiation. The results are presented as normalized survival fractions of log10 reduction in function of irradiation time. The error bars are standard deviation of each mean. Statistical differences are indicated by lower-case letters: a) represent differences in relation to the control strain, b) to the 0127:H7 strain, c) to the CTX-M-producing E. coli ST131 strain, d) to the MCR-1-positive E. coli ST10 strain and e) to the KPC-2-producing E. coli ST648 strain. Data is omitted in points where inactivation rate is greater than 7log10 such as for CTXM ST131 at irradiation times greater than 120 min and for KPC-2 ST648 at 180 min.
Acknowledgments We gratefully thank the Brazilian funding agency FAPESP (grants 2016/25095-2, 2016/08593-9 and 2015/13527-2), CAPES (Finance Code 001), CNPq (grant 141901/2016-0 and 312249/2017-9, 462042/ 2014-6 and 433128/2018-6), and technical support offered by the start52
Photodiagnosis and Photodynamic Therapy 27 (2019) 51–53
C. dos Anjos, et al.
up company BioLambda. N. L. is research fellow of CNPq (312249/ 2017-9). References
[9]
[1] A.J. Mathers, G. Peirano, J.D.D. Pitout, The role of epidemic resistance plasmids and international high-risk clones in the spread of multidrug-resistant Enterobacteriaceae, Clin. Microbiol. Rev. 28 (2015) 565–591, https://doi.org/10. 1128/CMR.00116-14. [2] F.P. Sellera, N. Lincopan, Zooanthroponotic transmission of high-risk multidrugresistant pathogens: a neglected public health issue, J. Infect. Public Health 12 (2019) 294–295, https://doi.org/10.1016/j.jiph.2018.12.013. [3] I. García-Meniño, V. García, A. Mora, D. Díaz-Jiménez, S.C. Flament-Simon, M.P. Alonso, et al., Swine enteric colibacillosis in Spain: pathogenic potential of mcr-1 ST10 and ST131 E. coli isolates, Front. Microbiol. 9 (2018) 1–15, https://doi. org/10.3389/fmicb.2018.02659. [4] T. Dai, A. Gupta, C.K. Murray, M.S. Vrahas, G.P. Tegos, M.R. Hamblin, Blue Light for infectious diseases: Propionibacterium acnes, Helicobacter pylori, and beyond? Drug Resist. Updat. 15 (2013) 223–236, https://doi.org/10.1016/j.drup.2012.07. 001.Blue. [5] C. Anjos, F.P. Sellera, R.G. Gargano, N. Lincopan, F.C. Pogliani, M.G. Ribeiro, et al., Algicidal effect of blue light on pathogenic Prototheca species, Photodiagn. Photodyn. Ther. 26 (2019) 210–213, https://doi.org/10.1016/j.pdpdt.2019.04. 009. [6] F.P. Sellera, M.R. Fernandes, R. Ruiz, A.C.M. Falleiros, F.P. Rodrigues, L. Cerdeira, et al., Identification of KPC-2-producing Escherichia coli in a companion animal: a new challenge for veterinary clinicians, J. Antimicrob. Chemother. 73 (2018) 2259–2261, https://doi.org/10.1093/jac/dky173. [7] F.P. Sellera, M.R. Fernandes, L. Sartori, M.P.N. Carvalho, F. Esposito, C.L. Nascimento, et al., Escherichia coli carrying IncX4 plasmid-mediated mcr-1 and blaCTX-M genes in infected migratory Magellanic penguins (Spheniscus magellanicus), J. Antimicrob. Chemother. 72 (2017) 1255–1256, https://doi.org/10.1093/jac/ dkw543. [8] A.P. Magiorakos, A. Srinivasan, R.B. Carey, Y. Carmeli, M.E. Falagas, C.G. Giske,
[10] [11]
[12]
[13]
[14]
[15]
[16]
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